Reddit mentions of StarTech.com 40 Pin Female IDE to SATA Adapter Converter - Connect a SATA device to an IDE controller - IDE to SATA Converter (IDE2SAT25)

As others have said, your options are somewhat limited. To run a SATA drive you've got two options - first a IDE-to-SATA converter module thingy, or two, a PCI-to-SATA card. I'd suggest you check out this website for more details:

http://lowendmac.com/2010/sata-and-ssd-options-for-g3-and-g4-power-macs/

The IDE-to-SATA converter might be the better option, as they're available new now and the system would boot and operate just like before. The PCI card might be technically better, but I don't know how easily available those SATA cards are anymore. Those Sonnet cards are excellent though, if you can find one for a reasonable price. eBay prices seem to be quite high. I would suspect that there are comparable cards too, but one of my concerns would be compatibility with whichever MacOS you choose to allow it to boot from SATA.

You might be able to use an IDE-to-SATA adapter like this one here:

https://www.amazon.com/Female-SATA-Adapter-Converter-bidirectional/dp/B001PYSAJI

Some musing from the 68kmla forum indicate that some PCI SATA cards based on the SIL3112 chipset, as well as some ACARD models may work. Exact models and availability may be a big issue these days though.

https://68kmla.org/forums/index.php?/topic/31402-beige-g3-pci-sata-is-it-an-option/

As for SSDs, I'm not sure how long-lived a SSD would run in a non-TRIM supported env, however I've certainly run Windows XP on SSDs and those worked for years. And of course there are people out there running CF cards in IDE slots that have no idea of TRIM at all without any trouble at all. Your mileage may vary depending on your use case, so they still might make sense.